Rotary engine oil metering pump

ABSTRACT

A rotary engine is provided with an oil metering pump having a stepped plunger and accommodating bore arrangement with a variable input speed drive from the engine&#39;&#39;s output which changes plunger strokes per unit time and a variable cam follower arrangement that is controlled in accordance with engine throttle opening to alter the length of plunger stroke per plunger revolution.

United States Patent [191 Morgan et a1.

[ ROTARY ENGINE OIL METERING PUMP [75] Inventors: Robert E. Morgan; James D. Palma,

both of Grand Rapids, Mich.

[73] Assignee: General Motors Corporation,

Detroit, Mich.

[22] Filed: June 26, 1972 [2| I Appl. No: 266,450

[52] US. Cl 418/84, 418/100, 417/228, 184/6.l6, 184/6.28, 123/801 [51] Int. Cl. F01c 21/04 [58] Field of Search 418/84, 100, 88; 417/228; 184/6.16, 6.28; 123/801 [5 6] References Cited UNITED STATES PATENTS 3,302,752 2/1967 Shiokawa 184/26 Oct. 9, 1973 4/1969 Atsumi 184/27 R 3/1972 Straubel 184/6.28

Primary Examiner-C. J. Husar Attorney-J. L. Carpenter et a1.

[57] ABSTRACT A rotary engine is provided with an oil metering pump having a stepped plunger and accommodating bore arrangement with a variable input speed drive from the engines output which changes plunger strokes per unit time and a variable cam follower arrangement that is controlled in accordance with engine throttle opening to alter the length of plunger stroke per plunger revolution.

3 Claims, 8 Drawing Figures PAIENTEUUET 9197s SHEET 2 IF 3 ROTARY ENGINE OIL METERING PUMP This invention relates to a rotary engine oil metering pump and more particularly to an oil metering pump that meters oil to lubricate an engine rotors gas seals in accordance with engine speed and throttle opening.

In rotary engines, it is desirable to meter oil to lubricate the engine rotors apex and side seals at a rate that increases with engine load. One way of doing this is to meter the oil at a rate that increases with increasing engine speed and torque demand as indicated by throttle opening. While there are presently commercial pumps that produce such oil metering operation, there is a continuing effort for simplification and reduction in size of the pump coupled with enhanced reliability and reduction in cost.

The rotary engine oil metering pump according to the present invention comprises a pump body having a stepped diameter bore that receives a stepped diameter plunger which is reciprocably and rotatably mounted therein and cooperates therewith to provide a variable volume chamber whose displacement is determined by the extent of reciprocal plunger movement or stroke. The p'unger is rotatably driven by the engines output shaft and a cam pivotably mounted in the pump body is operatively connected to the engines throttle and cooperates with a cam follower formed directly on one end of the plunger which is spring biased against the cam to effect reciprocal plunger movement on rotation of the plunger with the extent of such plunger stroke varying with the angular position of the cam. Oil inlet and outlet ports are open to the bore in the path of rotary motion of the plunger which is provided with a relieved portion that cooperates with the bore to define a passage that connects the inlet port to the chamber when the chamber is expanding and connects the chamber to the outlet port when the chamber is contracting whereby there is provided an oil rate that increases with increasing engine speed and throttle openmg.

An object of the present invention is to provide a new and improved rotary engine oil metering pump.

Another object is to provide a rotary engine oil metering pump having a plunger that defines with a pump body an expansible chamber with the plunger being driven by the engines output shaft and having a cam follower thereon that cooperates with a cam controlled according to engine throttle position to vary the plunger stroke so that there is effected an oil rate that increases with increasing engine speed and engine throttle opening.

Another object is to provide a rotary engine oil metering pump having a stepped diameter plunger received in a stepped diameter bore and cooperating therewith to provide an expansible chamber with the plunger being driven by the engine output at a speed proportional thereto and the plunger having a cam follower thereon that cooperates with a cam that is controlled according to engine throttle position to alter the plunger stroke per revolution of the plunger to provide an oil rate that increases with increasing engine speed and engine throttle opening.

These and other objects of the invention will become more apparent with reference to the following description and drawing in which:

FIG. 1 is an elevational view with parts in section of a rotary engine having an oil metering pump according to the present invention.

FIG. 2 is an enlarged view of the oil metering pump in FIG. 1.

FIG. 3 is a view of the oil metering pump taken along the line 33 in FIG. 2.

FIG. 4 is a view of the oil metering pump taken along the line 44 in FIG. 3.

FIG. 5 is a view of the oil metering pump taken along the line 5-5 in FIG. 2.

FIG. 6 is a view of the oil metering pump taken along the line 66 in FIG. 5.

FIG. 7 is a view of the oil metering pump taken along the line 7-7 in FIG. 2.

FIG. 8 is a view of the oil metering pump taken along the line 8-8 in FIG. 3.

Referring to FIG. 1, there is shown a rotary combustion engine 10 of the Wankel type having an oil metering pump 12 according to the present invention that meters oil to lubricate the engines gas seals. The engine 10 comprises a stationary outer body or housing 13 having a rotor cavity that is defined by an inwardly facing peripheral wall 14 and a pair of axially spaced opposed side walls 16, only one of which is shown. In the Wankel engine the peripheral wall 14 is in the shape of a two-lobed epitrochoid or a curve parallel thereto and a rotor 18 having the general shape of a triangle with three convex peripheral faces 20 is mounted within the rotor cavity on an eccentric 22 of a crankshaft 24 which is rotatably mounted outboard of the rotor cavity in the side walls 16 and aligned with the rotor cavitys axis. An annular externally toothed gear 26 is received about and is concentric with the crankshaft 24 and is rigidly secured to the engine housing 13. The gear 26 meshes with an internally toothed gear 28 that is concentric with and fixed to the rotor 18. The gear 28 has one and one-half times the number of teeth as the gear 26 with the result that this gearing enforces a fixed cyclic relation between the rotor and the crankshaft such that the crankshaft which is the engines output shaft makes three complete revolutions for every one complete revolution of the rotor. The rotor faces 20 cooperate with the peripheral wall 14 and with the side walls 16 to define three variable volume working chambers 30 that are spaced around and move with the rotor within the housing as the rotor rotates about its axis while planetating with respect to the output axis.

A carburetor 32 supplied with fuel from a fuel tank 34 by a fuel pump 36 delivers an air-fuel mixture to an intake manifold 38 under the control of the carburetors throttle valve whose opening is controlled by a throttle lever 40 that is connected at one end to the throttle valves shaft 41. The other end of lever 40 is connected to a rod 42 that is linked to an accelerator pedal, not shown, for control by the vehicle operator, the throttle valve arrangement being such that it is opened when the throttle lever 40 is pivoted in a counterclockwise direction as viewed in FIG. 1. The intake manifold 38 is connected to an intake port 44 which opens to the rotor cavity through the peripheral wall 14. On rotor rotation in the direction indicated by the arrow in FIG. 1, air-fuel mixture is sequentially periodically admitted to the chambers 30 by the traversing motion of the rotor apexes relative to the intake port 44 whereafter the air-fuel mixture is trapped and then compressed in readiness for ignition. Sequential ignition of the air-fuel mixture in the chambers 30 is effected by two spark plugs 46 and 48 which receive timed ignition pulses from a distributor 50 whose shaft 52 is driven by the crankshaft 24, this drive being effected by a pinion 54 that is connected to the lower end of the distributor shaft 52 and meshes with a worm gear that is formed on the crankshaft 24. The two spark plugs 46 and 48 are on the side of the peripheral wall 14 opposite the side where the intake port 44 is located and are peripherally spaced thereabout so that the plug 46 is said to lead the other plug 48. The spark plugs 46 and 48 may be tired together or only one plug fired according to certain engine operating conditions as is well known in the art. With combustion, the peripheral wall 14 takes the reaction to force the rotor to continue rotating and eventually each working chamber following the expansion phase, is exhausted during an exhaust phase to an exhaust manifold 58 via an exhaust port 60 that is open to the rotor cavity through the peripheral wall 14 and is periodically traversed by the rotor apexes.

Sealing of the chambers 30 is effected by apex seals 62 each of which extends the width of the rotor and is mounted at a rotor apex, corner seals 64 each of which is mounted in a rotor side at each rotor apex, and side seals 66 each of which is mounted in a rotor side and extends between pairs of corner seals with the corner seals each providing a sealing link between the adjacent ends of two side seals and one apex seal. The apex seals 62 are urged radially outward by spring means, not shown, to continuously engage the peripheral wall 14 and both the corner seals 64 and side seals 66 on both rotor sides are urged axially outward by suitable spring means, not shown, to continuously engage the side walls 16. I

Having thus described a single rotor arrangement, it will be understood that the engine may have one or more additional rotors with suitable air-fuel, ignition and exhaust provisions as is well known in the art. The oil metering pump 12 is adaptable to meter oil. to either a single or a dual rotor arrangement to lubricate the apex seals 62 and also the corner seals 64 and side seals 66 to minimize the wear of these gas seals and the rotor cavity walls.

Describing now the oil metering pump 12, there is a pump body 68 which is secured by two bolts 70 to the rotary engines housing 13 as shown in FIG. 1. As best shown in FIGS. 3 and 4, the pump body 68 has a stepped bore 72 having a small diameter portion 74 which is closed at its right-hand end and a large diameter portion 76 which is open at its left-hand end. A stepped diameter plunger 78 having a small diameter land 80 and a large diameter land 82 is rotatably and reciprocally mounted in the stepped bore 72 with the lands 80 and 82 closely fitting the bore portions 74 and 76, respectively. The stepped diameter plunger 78 cooperates with the stepped bore 72 to provide a variable volume chamber 84 between the steps of the plunger and the step of the bore whose volume decreaseson rightward stroke of the plunger. The left-hand end of the pump body 68 which has a cavity 85 providing access to the left-hand end of bore 72 is closed by a cover plate 86 that is secured in place by screws 87.

Oil supply to the oil metering pump 12 is from the engines pressurized lubrication system which includes a passage 79, this communication being via a port 88 that aligns with passage 79 and is located in the interface of the pump body 68 that seats on the engine housing as shown in F IG, 3. The port 88 is connected by passages 89 and 90 via cavity 85 .to inlet ports 92 and 94 that open to the stepped bore 72 through the large diameter portion 76 at diametrically opposite locations. Referring to FIGS. 3 6, the inlet ports 92 and 94 are sequentially periodically connected .to the chamber 84 by a passage in the large diameter bore portion 76 provided by a flat 96 on the large diameter land 82 that extends axially from the right-hand end of land 82 to a point to the left of the inlet ports 92 and 94 when the plunger is in its maximum rightward stroke position. This passage between the large diameter land 82 and the large diameter portion 76 also provides for sequential periodic connection of the chamber 84 to two outlet ports 97 and 98 which are open to the large diameter portion 76 at the same axial location as the inlet ports 92 and 94 and are located diametrically opposite each other at to the inlet ports 92 and 94, the flat 96 having a chordal dimension as viewed in FIG. 5 such that there is preferably no overlap between adjacent inlet and outlet ports. The outlet ports 97 and 98 are connected to threaded outlet openings 100 and 102, respectively. The threaded outlet openings 100 and 102 receive pipe fittings 104 and 106 as shown in FIGS. 2 and 5 which serve to connect these outlets to oil pipes 108 and 110, The oil pipe 108 being connected as shown in FIG. 1 to the carburetor 32 to supply oil thereto and the other oil pipe 110 being for similar connection where there is another rotor. The oil thus delivered is mixed with the fuel and then fed with the fuel through the intake port to'the rotor cavity where it is distributed to lubricate the gas seals as they slide on the housing walls. It will be understood that the oil thus delivered to the carburetor may be mixed with the fuel in the carburetors float chamber or may be delivered directly into the carburetors jet circuit or into the airstream in the carburetor throat.

The plunger 78 is rotated in the direction indicated by the arrow in FIGS. 5 and 7 at a speed proportional to engine speed by a pair of worm gear drives between the plunger and the distributor shaft 52 which is directly driven by the engines crankshaft 24. As shown in FIG. 7, one of these gear drives comprises a worm gear 114 that is formed on the distributor shaft 52 between the distributor 50 and the pinion 54. The worm gear 114 meshes with a pinion 116 which is pinned to a'pump'drive shaft 118 that is journaledin the pump body 68 for rotation about an axis that is at right angles to the axis ofthe plunger 78, this journaling being provided at one axial location by the small diameter portion of a stepped bore 120 that is closed at its righthand end and at another axial location by a bushing 122 that is secured in the larger stepped diameter portion of the bore 120. An O-ring 123 mounted in a circumferential groove in bushing 122 retains the bushing in bore 120. The pump drive shaft 118 between the bushing 122 and the small diameter portion of bore 120 has formed thereon a worm gear 124 which meshes with a pinion 126 that is formed on an intermediate portion of the large diameter land 82 of plunger 78. The teeth of pinion 126 are elongated in the axial direction as shown in FIG. 4 and have a slight helix to permit the plunger 78 to move axially in its bore at right angles to worm gear 124 while the worm gear 124 and pinion 126 remain engaged to rotate the plunger, the elongation of the pinion 126 exceeding the maximum stroke of the plunger.

Reciprocation of the plunger 78 is effected by a spring 128 which as best shown in FIG. 3 is seated at its right-hand end on a rotary spring seat 130 piloted on the right-hand end of bore 72 and is seated at its lefthand end on an internal shoulder 131 of the plunger 78. The spring 128 is prestressed to bias the plunger leftward so that cam follower 132 formed on the left-hand end of plunger 78 is continually maintained in engagement with a cam 134 which is formed on a camshaft 136. A passage 135 in the plunger 78 connects the chambers at the opposite ends of the plunger to minimize the spring force required by effecting a zero pressure differential between these chambers and also provides for fluid displacement in these chambers to prevent hydraulic lock. Furthermore, the pressure in the pump chamber 84 acts on the plunger 78 in the same direction as the spring 128 to assist the cam engagement and thereby further minimize the spring force required. The camshaft 136 is mounted in a bore 137 in the pump body 68 for angular movement about an axis which intersects and is at right angles to the axis of the plunger 78. As shown in FIG. 8, a roll pin 138 pinned to the pump body 68 is received in a circumferential groove 139 in the camshaft 136 to prevent axial camshaft movement while permitting angular movement thereof. As shown in FIGS. 2 and 3, one end of the cam-shaft 136 extends outward of the pump body 68 and is fixed to a lever 142 by having a non-circular portion received in a corresponding aperture in the lever, this connection being maintained by a nut 140 threaded to shaft 136. An O-ring 143 mounted in a circumferential groove in camshaft 136 prevents oil leakage out of bore 137. The other end of the lever 142 has a socket 144 pivotally secured thereto. The socket 144 has an aperture 146 slidably receiving a linkage rod 148 which at its right-hand end has a snap ring 149 and receives a coil spring 150 between the socket 144 and the snap ring 149. As shown in FIG. 1, the other end of rod 148 is pivotally secured to a lever 152 which is journaled on the carburetors throttle shaft 41 and is engaged by a tang 153 on the throttle lever 152 to pivot counterclockwise with the throttle lever. A stop arm 154 integral with the cam-shaft lever 142 has an adjustable stop provided by a screw 155 threaded thereto which is engageable with the pump body 68 as shown in FIG. 2 to determine the minimum plunger stroke position as described in more detail later. The camshaft 136 is biased to this minimum stroke position by a torsion spring 156 which is arranged about the camshaft axis and engages at its opposite ends the pump body 68 and lever 142 as shown in FIGS. 2 and 3, this torsion spring force urging counterclockwise cam-shaft movement as viewed in FIG. 2. The coil spring 150 maintains the lever 152 against tang 153 and also yields to permit rod 148 to slide in socket 144 as the rod is pulled leftward beyond the maximum travel of oil metering pump arm 142.

The cam follower 132 has a profile wherein there is a center line 157 which is located 45 from the flat 96 and perpendicular to the plunger axis and extends the full diameter of the large land 82 as shown in FIG. 4 with the profile at 90 from the center line 157 being convex and extending axially on an increasing radius to points 158 on land 82 which lie on a diameter at 90 to center line 157 which results in a V-shape with a rounded end as shown in FIG. 3. The cam 134 has a cylindrical land 160 having a concave recess 162 with a center line 164 lying on a plane which is perpendicular to the camshaft axis and passes through the axis of the plunger 78. The width of the recess 162 in the axial direction is less than the length of the center line 157 of the cam follower so that the cam follower rides up onto the camshaft land 160 and bridges the recess 162 as the cam follower center line 157 passes perpendicular to the recess center line 164. As shown in FIG. 4, the depth of the camshaft recess 162 at the center line 164 gradually increases in the counterclockwise direction so that there is a progressively increasing depression with clockwise camshaft movement on increasing throttle opening. With this geometry of the cam 134 and cam follower 132, there are effected two complete reciprocating strokes of the plunger 78 for every complete plunger revolution wherein the center line 157 of the cam follower 132 spans the cam recess 162 to contact the land 160 to determine maximum rightward movement of the plunger 78 and contacts the center line 164 of the recess 162 to determine maximum leftward plunger movement. Thus, with the two inlet ports 92 and 94 and the two outlet ports 96 and 98 there will occur a complete pumping cycle every 180 or half revolution of the plunger 78 with the fiat 96 providing the proper connections during the intake and exhaust phase of each pumping cycle by its angular location relative to the cam follower center line 157 wherein an intake port is connected to the chamber 84 as the cam follower 132 slides down into the cam recess 162 and then as the cam follower slides up out of the cam recess the chamber is connected to the outlet port that is located ahead of the previously connected inlet port.

Describing now the oil metering operation, the plunger 78 is driven through the worm gear drives by the engine crankshaft at a speed proportional thereto and with the engine throttle opened to position the cam 134 at some intermediate stroke position the plunger 78 by its rotation is caused to reciprocate by the spring biased cam follower 132 following the cam 134. With oil made available to the port 88 from the engines pressurized lube system, oil fills the chamber 84 as it expands in one of its expansion phases during 90 plunger rotation by communication with one of the inlet ports 92 and 94 via the passage formed by the flat 96. On continuation of plunger rotation through another 90, the flat 96 closes off the connection of this intake port and then connects the chamber 84 as it contracts during its subsequent compression phase to the outlet port which the flat 96 next passes. This pumping cycle is thus completed during one-half of a plunger revolution and is repeated during the remaining half of plunger revolution using the other inlet port and outlet port. When the engine throttle is opened further, the limit of rightward movement of the plunger 78 is not changed since this is determined by the cam land but the limit of leftward plunger movement is increased by the increase in cam recess depth so that there is effected a corresponding increase in pump displacement and thus in the rate of oil pumped assuming there is no change in engine speed. When the rotary speed of the plunger 78 increases with increasing speed, the pumping cycles per unit of time increase accordingly and thus the oil is metered to the outlet ports at a rate which increases with both increasing throttle opening and engine speed. It will also be understood that for engines with only one rotor, the pump is easily adapted thereto by simply connecting one of the outlets back to the pump inlet so that what would be the normal pump output at this one outlet is bypassed back to the pump inlet. Furthermore, it will be understood that the oil supply to the pump may be by gravity feed instead of by the engines pressure supply.

The above described embodiment is illustrative of the invention which may be modified within the scope of the appended claims.

We claim:

1. An oil metering pump for a rotary engine having gas seals, an output shaft and a throttle, said pump comprising a pump body having a stepped diameter bore, a stepped diameter plunger reciprocably and rotatably mounted in said bore and cooperating therewith to provide a variable volume chamber between the steps of said bore and said plunger having a displacement determined by the extent of plunger stroke, means drivingly connecting said output shaft to rotate said plunger while permitting said plunger to reciprocate, a cam pivotably mounted in said pump body, means operatively connecting said throttle to vary the angular position of said cam with the opening of said throttle said plunger having a cam follower at one end contactable with said cam, a spring arranged in said bore between said plunger and said pump body for continuously biasing said cam follower to follow said cam, said cam and said spring biased cam follower cooperating to effect reciprocal plunger movement on rotation of said plunger with the plunger stroke varying with the angular position of said cam, an inlet port for receiving oil open to said bore in the path of rotary motion of said plunger, an outlet port for delivering oil to lubricate said gas seals open to said bore in the path of rotary motion of said plunger, and said plunger having an external relieved portion cooperating with said bore to define a passage for successively connecting said inlet port to said chamber when said chamber is expanding and said chamber to said outlet port when said chamber is contracting during one plunger revolution.

2. An oil metering pump for a rotary engine having gas seals, an output shaft and a throttle, said pump comprising a pump body having a stepped diameter bore, a stepped diameter plunger reciprocably and rotatably mounted in said bore and cooperating therewith to provide a variable volume chamber between the steps of said bore and said plunger having a displacementdetermined by the extent of plunger stroke, means drivingly connecting said output shaft to rotate said plunger whie permitting said plunger to reciprocate, a cam pivotably mounted in said pump body, means operatively connecting said throttle to vary the angular position of said cam with the opening of said throttle said plunger having a cam follower at one end contactable with said cam, a spring arranged in said bore between said plunger and said pump body for continuously biasing said cam follower to follow said cam, said cam and said spring biased cam follower cooperating to effect two complete reciprocating plunger strokes on one complete rotation of said plunger with the plunger stroke varying with the angular position of said cam to increase plunger stroke with increasing throttle opening, a pair of inlet ports for receiving oil open to said bore at diametrically opposite locations in the path of rotary motion of said plunger, a pair of outlet ports for delivering oil to lubricate said gas seals open to said bore at diametrically opposite locations in the path of rotary motion of said plunger, said plunger having an external relieved portion cooperating with said bore to define a passage for successively connecting one of said inlet ports to said chamber when said chamber is expanding and said chamber to one of said outlet ports when said chamber is contracting during one-half of a plunger revolution and also for successively connecting the other of said inlet ports to said chamber when said chamber is expanding and said chamber to the other of said outlet ports when said chamber is contracting during the remaining one-half of a plunger revolution.

3. An oil metering pump for a rotary engine having gas seals, an output shaft and a throttle, said pump comprising a pump body having a stepped diameter bore, a stepped diameter plunger having a large diam eter land and a small diameter land reciprocably and rotatably mounted in said bore and cooperating therewith to provide a variable volume chamber between the steps of said bore and said plunger having a displacement determined by the extent of plunger stroke, means drivingly connecting said output shaft to rotate said plunger while permitting said plunger to reciprocate, a cam pivotably mounted in said pump body, means operatively connecting said throttle to vary the angular position of said cam with the opening of said throttle said plunger having a cam follower at one end contactable with said cam, a spring arranged in said bore between said plunger and said pump body for continuously biasing said cam follower to follow said cam, said cam and said spring biased cam follower cooperating to effect reciprocal plunger movement on rotation of said plunger with the plunger stroke varying with the angular position of said cam, to increase plunger stroke with increasing throttle opening an inlet port for receiving oil open to said bore in the path of rotary motion of said large diameter land of said plunger, an outlet port for delivering oil to lubricate said gas seals open to said bore in the path of rotary motion of said large diameter land of said plunger, and said large diameter land of said plunger having a relieved portion openable to said ports throughout the range of plunger stroke cooperating with said bore to define a passage for successively connecting said inlet port to said chamber when said chamber is expanding and said chamber to said outlet port when said chamber is contracting during one plunger revolution. 

1. An oil metering pump for a rotary engine having gas seals, an output shaft and a throttle, said pump comprising a pump body having a stepped diameter bore, a stepped diameter plunger reciprocably and rotatably mounted in said bore and cooperating therewith to provide a variable volume chamber between the steps of said bore and said plunger having a displacement determined by the extent of plunger stroke, means drivingly connecting said output shaft to rotate said plunger while permitting said plunger to reciprocate, a cam pivotably mounted in said pump body, means operatively connecting said throttle to vary the angular position of said cam with the opening of said throttle said plunger having a cam follower at one end contactable with said cam, a spring arranged in said bore between said plunger and said pump body for continuously biasing said cam follower to follow said cam, said cam and said spring biased cam follower cooperating to effect reciprocal plunger movement on rotation of said plunger with the plunger stroke varying with the angular position of said cam, an inlet port for receiving oil open to said bore in the path of rotary motion of said plunger, an outlet port for delivering oil to lubricate said gas seals open to said bore in the path of rotary motion of said plunger, and said plunger having an external relieved portion cooperating with said bore to define a passage for successively connecting said inlet port to said chamber when said chamber is expanding and said chamber to said outlet port when said chamber is contracting during one plunger revolution.
 2. An oil metering pump for a rotary engine having gas seals, an output shaft and a throttle, said pump comprising a pump body having a stepped diameter bore, a stepped diameter plunger reciprocably and rotatably mounted in said bore and cooperating therewith to provide a variable volume chamber between the steps of said bore and said plunger having a displacement determined by the extent of plunger stroke, means drivingly connecting said output shaft to rotate said plunger while permitting said plunger to reciprocate, a cam pivotably mounted in said pump body, means operatively connecting said throttle to vary the angular position of said cam with the opening of said throttle said plunger having a cam follower at one end contactable with said cam, a spring arranged in said bore between said plunger and said pump body for continuously biasing said cam follower to follow said cam, said cam and said spring biased cam follower cooperating to effect two complete reciprocating plunger strokes on one complete rotation of said plunger with the plunger stroke varying with the angular position of said cam to increase plunger stroke with increasing throttle opening, a pair of inlet ports for receiving oil open to said bore at diametrically opposite locations in the path of rotary motion of said plunger, a pair of outlet ports for delivering oil to lubricate said gas seals open to said bore at diametrically opposite locations in the path of rotary motion of said plunger, said plunger having an external relieved portion cooperating with said bore to define a passage for successively connecting one of said inlet ports to said chamber when said chamber is expanding and said chamber to one of said outlet ports when said chamber is contracting during one-half of a plunger revolution and also for successively connecting the other of said inlet ports to said chamber when said chamber is expanding and said chamber to the other of said outlet ports when said chamber is contracting during the remaining one-half of a plunger revolution.
 3. An oil metering pump for a rotary engine having gas seals, an output shaft and a throttle, said pump comprising a pump body having a stepped diameter bore, a stepped diameter plunger having a large diameter land and a small diameter land reciprocably and rotatably mounted in said bore and cooperating therewith to provide a variable volume chamber between the steps of said bore and said plunger having a displacement determined by the extent of plunger stroke, means drivingly connecting said output shaft to rotate said plunger while permitting said plunger to reciprocate, a cam pivotably mounted in said pump body, means operatively connecting said throttle to vary the angular position of said cam with the opening of said throttle said plunger having a cam follower at one end contactable with said cam, a spring arranged in said bore between said plunger and said pump body for continuously biasing said cam follower to follow said cam, said cam and said spring biased cam follower cooperating to effect reciprocal plunger movement on rotation of said plunger with the plunger stroke varying with the angular position of said cam, to increase plunger stroke with increasing throttle opening, an inlet port for receiving oil open to said bore in the path of rotary motion of said large diameter land of said plunger, an outlet port for delivering oil to lubricate said gas seals open to said bore in the path of rotary motion of said large diameter land of said plunger, and said large diameter land of said plunger having a relieved portion openable to said ports throughout the range of plunger stroke cooperating with said bore to define a passage for successively connecting said inlet port to said chamber when said chamber is expanding and said chamber to said outlet port when said chamber is contracting during one plunger revolution. 